1. Field of the Invention
This invention relates to switchgear for electric power distribution systems. More particularly, it relates to an arrangement for mounting a heater within the switchgear cabinet.
2. Background Information
Switchgear assemblies for electric power distribution systems include electrical apparatus housed in metal cabinets with associated conductors such as bus bars and cabling for connecting the electrical apparatus in the distribution system. Typically, the electrical apparatus includes switching devices such as circuit breakers or network protectors which provide protection, and switches without protection such as disconnect switches for isolating parts of the distribution system, and transfer switches for connecting the distribution system to alternative power sources. The electrical apparatus can also include instrumentation such as metering equipment. Typically the cabinets are compartmentalized with the switching apparatus mounted in cells in a forward compartment, rigid bus bars located in a middle compartment and cabling terminated in a rear compartment.
Under certain operating conditions, typically low current and idle conditions, condensation can form in the cabinets. It is common to provide heaters which induce convective circulation of air through the compartments to control condensation. It is relatively easy to access and service the heaters in the forward and rear compartments. However, the heater in the middle, bus bar compartment, is much more difficult to service because of the presence of the rigid bus bar assemblies and the insulative barriers between them. Presently, cabling in the rear compartment, access panels and the barriers in the middle compartment must be rearranged or removed and the rigid bus bar configuration must be contended with to reach the middle compartment heater.
There is a need, therefore, for an arrangement for mounting the heaters, and particularly those in the middle compartments of switchgear assemblies, which can be more easily serviced.